The existence of an electron shock structure in the electrical breakdown of nitrogen

Experimental evidence is presented to show the existence of a regularly repeating structure in the luminous core that appears during the final stage in the electrical breakdown of N2 at atmospheric pressure. A simple analysis identifies this pattern as an electron shock structure in the inviscid core of an underexpanded jet originating at the cathode spot. The results support the concept of wave propagation through the collision-dominated electrons.